Bent end incandescent lamp



March 5, 1963 E. B. NOEL ETAL BENT END INCANDESCENT LAMP Filed Dec. 11, 1959 h or A lnven tovs'. Edward B. NoeL, ViC lTOT A. Levan-d,

b3 flfif Their A t ovneg United States Patent 3,080,497 BENT END INCANDEfiCENT LAMP Edward B. Noel, Cleveland Heights, and Victor A. Levand, Lyndhurst, Ohio, assignors to General Electric Company, a corporation of New York Filed Dec. 11, 1959, Ser. No. 859,053 3 Claims. (Cl. 313-43) Our invention relates to electric incandescent lamps, and more particularly to elongated tubular double-ended lamps having a filament extending longitudinally of the tubular envelope and connected at its ends to the inner ends of lead-in wires which extend outwardly through hermetic seals at the extremities of the envelope.

it is an object of our invention to provide tubular incandescent lamps having laterally extending end portions which preferably extend at right angles to the main body portion of the envelope. Such a construction not only shortens the dead space between successive lamps arranged in end-to-end relationship but, even more importantly, it enables the lamps to be mounted with the atermly extending end portions projecting outwardly through the walls of a fixture or other support or enclosure and thereby protected from high temperatures and oxidation of the exposed lead-in wires. Such a .ructure is particularly useful in infrared or heat lamps having an envelope of quartz and lead-in wires of molybdenum wherein the molybdenum lead wires are subject to oxidation with resultant destruction of the hermetic seal.

Brie-fly stated, and in accordance with one aspect of our invention, the lamp comprises a tubular envelope of vitreous material such as glass or quartz, and lead-in wires of greater than normal length, each of the end portions of the envelope enclosing the lead-in wires being compressed at two spaced areas, the outermost compressed area being hermetically sealed to the respective lead-in wires, and the envelope being bent at the innermost compressed areas along with the portions of the lead-in wires enclosed thereby.

Further features and advantages of our invention will aapear from the following description of species thereof and from the drawing wherein:

FIGS. 1 to 4- are elevations, in section, showing various steps in the manufacture of a lamp comprising our invention;

F163. 5 and 6 are sections of compressed portions of the lamp envelope taken along the respective lines 5-5 in FIG. 2 and 6-6 in F1633;

PEG. 7 is a perspective view of one end of the lamp;

FIG. 8 is an elevation, in section, illustrating a moditied method of making the lamp; and

FIGS. 9 and 10 are elevations illustrating steps in another modification of the method of manufacture.

One method of manufacturing a lamp comprising our invention is shown in FIGS. 1 to 4. As shown in FIG. 1, an elongated tubular envelope 1 of vitreous material is assembled with a mount structure comprising a coiled tungsten wire filament 2, a plurality of supports 3 and lead-in wires 4. The supports 3 are preferably tantalum disks of the type disclosed and claimed in Patent 2,813,- 993, Fridrich; they are attached at spaced intervals along the length of the filament 2 and are of slightly smaller diameter than the envelope 1 and serve to support the filament from the inner walls of the envelope. The leadin wires 4 are of longer than normal length, are secured at their inner ends to respective ends of the filament 2, and extend longitudinally to the exterior of the envelope 1. With an envelope 1 of quartz, the leads a are preferably of molybdenum wire having a very thin intermediate foliated or ribbon portion 5 for making a hermetic seal with the quartz envelope.

3,633,497 Patented Mar. 5, 1%63 For gas filling the envelope 1 and sealing the filament mount structure therein, the assembly is preferably an ranged vertically in apparatus similar to that shown in Patent 2,855,265, Poote et al. The filament mount structure is suspended from an apertured cap 6 which is threaded over the outer end of the upper lead wire 4 and which has a rubber stopper portion 7 which is pushed into the upper end of the envelope 1 to plug that end and close it oif from the atmosphere. The lead wire 4 is gripped between an adjustable screw 8 in the body of the cap and the end of a clamping lever 9 which is pivoted on a pin 1i) and is held in a normally closed position by the expansion of a spring 11. The outer end of the lower lead 4 is pulled down to stretch the filament 2 slightly and is clamped in an aperture in a chuck 12.

The air in the envelope 1 is displaced by a how of inert gas, such as argon, which is introduced into the envelope through a tribulation 13 at the center thereof and which fiows out of the envelope through the lower end thereof.

Shortly after starting the gas flow, the envelope l is heated and softened in an area around the inner end of the lower lead wire 4 and is then pinched upon the lead wire by suitably shaped jaws to form the compressed or collapsed portion 14 shown in FIG. 2. The said portion i4 is only partially collapsed, preferably to an I-shaped cross section as shown in FIG. 6, to leave a pair of longitudinally extending passages or crevices 15 through the interior thereof and through which the inert gas continues to tlow out of the envelope.

In the next step, the lower extremity of the envelope 1 is then heated and softened and subsequently pinched upon the ribbon portion 5 of the lower lead wire 4 to form the compressed and pinched sea-1 portion 16 shown in FIGS. 3 and 5 which hermetically seals the lower end of the envelope. At this time, the pressure of the inert gas in the envelope is preferably prevented from rising sufficiently to distort the plastic seal area by a suitable relief valve; a suitable form of such relief valve is shown in the aforesaid Foote et al. Patent 2,855,265.

The cap 6 is then removed from the upper end of the envelope 1, and the envelope is inverted and the outer end of the then lowermost lead wire 4 is threaded into the chuck 12. During all this time the flow of inert gas is maintained through the tubulation 13 to drive out any air which may have been pocketed in the end of the envelope which was originally uppermost.

The operator then repeats the steps of first fusing and partially compressing the envelope 1. at the area. surrounding the inner end of the lead wire 4, as shown at 14 in FIGS. 2 and 6, and then fusing and pinching the lower extremity of the envelope to form a hermetic seal as shown at 16 in FIGS. 3 and 5.

Upon completion of the sealing operation, the lamp, with the inert gas pressure therein equalized and maintained close to atmospheric by virtue of a suitable relief valve in the supply line, may be placed in a suitable forming jig, heated and softened at the compressed areas 14 and bent at those areas to form end or leg portions 17 (FIG. 4) extending laterally from the main body portion of the envelope containing the filament 2. Then the tubulation 13 is fused and tipped off at 18 with the inert gas retained in the envelope 2. as the permanent gas filling.

The preferred I-shaped (or H-shaped) cross section of the bent compressed area 14 not only provides a convenient manner of forming the passages 15, but serves to provide desirable added strength to the lateral end. As illustrated in FIGS. 4 and 7, the compressed portions 14 are preferably bent along the plane including the web portion of the I-shaped section. Also as shown, the flattened seal portions 16 are in planes normal to the plane containing the U-shaped envelope, but they may be oriented 90 to be in that plane. Also, when desired, the hermetic seals 16 may be formed to an I-shaped section similar to that shown in FIG. 6 but completely collapsed to avoid the presence of the passages 15; in that event, both of the compressed areas 14 and 16 may be formed by the same pair of pinch jaws by arranging that they do not close fully upon the area 14 so as to leave the passages 15 therethrough.

When used as a source of infrared radiation, the lamp may be placed with the main body portion of its envelope in the interior of an enclosure such as a furnace or reflector, and its end or leg portions 17 extending outwardly through openings in the wall of the enclosure. In that way, the outer exposed ends of the lead wire 4 are protected from high temperatures and oxidation which would cause the seals 16 to crack and thereby destroy the hermetic seal.

The lamp may be made of a tipless construction by a method which, in its preliminary steps, is a modification of that disclosed in Patent 2,900,771, Levand. As shown in FIG. 8, the assembly of envelope 1 and mount structure including filament 2 and lead wires 4 is preferably disposed in a vertical position with its upper end (not shown) tightly plugged, for example by a cap like that shown at 6 in FIG. 1. The inert gas is directed into the lower end of the envelope 1 through a hollow needle 20 to flush the interior of the envelope. The envelope is then softened and partially compressed or collapsed at the area 14 to produce the I-beam shaped section shown in FIG. 6 with the passages 15 which permit the flow of gas to continue. Then the lower extremity of the envelope is heated to a plastic condition, the needle 20 is withdrawn, and the plastic area is compressed as shown at 16 in FIGS. 3 and to form a hermetic seal about the ribbon portion 5 of the lead Wire 4. The lamp is then inverted, the

cap 6 is removed, the needle 20 is inserted into the then lower end of the envelope, and the envelope is heated and compressed at the areas 14 and 16 (FIGS. 2 and 3) in the same manner as described above, the envelope 1 being thereby permanently sealed with the gas filling contained therein at a pressure which may be some 500600 mm. of Hg at room temperature. The lamp may then be heated and bent at the areas 14 to a form in all respects like that shown in FIG. 4 except for the absence of the tip 18.

The method described immediately above may be modified by flushing the envelope 1 with inert gas from the top, forming the compressed area 14 adjacent the lower end and the seal 16 at the lower extremity, and then inverting the envelope, flushing with gas through the needle 20 and forming the compressed areas 14 and 16 as described above in connection with FIG. 8.

In FIGS. 9 and we have illustrated the preliminary steps of a presently preferred method. In this case, the envelope 1 is flushed and filled with inert gas at a pressure somewhat below atmospheric, and the extremities of the envelope are hermetically sealed at 16 in any suitable manner but preferably by one of the methods disclosed in either of the aforementioned Patents 2,900,771, Levand, or 2,855,265, Foote et al. One of those methods would be like that described above in connection with FIGS. 1 and 3 and omitting the formation of the compressed areas 14; the other method would be like that described in connection with FIG. 8 and again omitting the compressed areas 14.

The portions of the envelope surrounding the inner ends of the elongated lead wires 4 are then heated by opposed burners 21 (FIG. 10) which emit elongated narrow flames, and the heating is continued to cause the envelope to collapse to an I-shaped section 14 essentially like that shown in FIG. 6. However, in this case it is immaterial whether the passages 15 remain or whether a hermetic seal is formed at the section 14. It is preferred that the two compressed areas 14 adjacent respective ends of the envelope be formed successively in order to avoid heating the gas filling in the envelope 1 to a temperature so high as to increase its pressure sufiiciently to form a bulge in the plastic envelope material in the vicinity of the area 14. While the envelope material in each area 14 is still plastic from the collapsing operation, it may be bent to the form shown in FIG. 4.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A double-ended elongated electric incandescent lamp comprising a sealed gas-filled tubular envelope of vitreous material, an elongated current supply lead-in wire extending from the exterior at each end of said envelope a substantial distance inwardly of the envelope, an incandescible filament extending longitudnially ofi only a main body portion of said envelope between the inner ends of said lead-in wires and connected directly to said wires, seal portions at the extremities of said envelope com pressed upon and hermetically sealed to localized portions of the respective lead-in wires extending therethrough, localized pinch portions of said envelope spaced from respective said seal portions and compressed upon localized portions of the said respective lead-in wires adjacent their inner ends, the ends of said envelope beyond respective p nch portions extending laterally of and a substantial distance beyond the main body portion by virtue of a bend at respective said pinch portions.

2. A lamp as set forth in claim 1 wherein the said pinch portions of the envelope are of generally I-shaped cross section and the bend is along the plane including the web portion of the I-shaped section.

3. A double-ended elongated electric incandecent lamp comprising a sealed gas-filled tubular envelope of vitreous material, an elongated current supply lead-in wire extending from the exterior at each end of said envelope a substantial distance inwardly of the envelope, an incandescible filament extending longitudinally ofi a main body portion of said envelope between the inner ends of said lead-in wires and connected to said wires, seal portrons at the extremities of said envelope compressed upon and hermetically sealed to localized portions of the respective lead-in wires extending therethrough, localized pinch portions of said envelope spaced from respective sa1d seal portions and compressed upon localized portions of respective lead-in wires adjacent their inner ends, the ends of said envelope beyond respective pinch portions extending laterally of and a substantial distance beyond the main body portion by virtue of a bend at respective said pinch portions, the said pinch portions of the envelope having longitudinal passages throughout aflcrding communication between the said main body portion of the envelope and the respective laterally extending end portions of the envelope.

References Cited in the file of this patent UNITED STATES PATENTS 263,304 'Betts Aug. 29, 1882 2,056,665 Frech Oct. 6, 1936 2,225,465 Scharfnagel Dec. 17, 1940 2,342,044 Foote Feb. 15, 1944 2,486,497 Salneu Nov. 1, 1949 2,523,033 Leighton Sept. 19, 1950 2,910,605 Hodge Oct. 27, 1959 

1. A DOUBLE-ENDED ELONGATED ELECTRIC INCANDESCENT LAMP COMPRISING A SEALED GAS-FILLED TUBULAR ENVELOPE OF VITREOUS MATERIAL, AN ELONGATED CURRENT SUPPLY LEAD-IN WIRE EXTENDING FROM THE EXTERIOR AT EACH END OF SAID ENVELOPE A SUBSTANTIAL DISTANCE INWARDLY OF THE ENVELOPE, AN INCANDESCIBLE FILAMENT EXTENDING LONGITUDINALLY OF ONLY A MAIN BODY PORTION OF SAID ENVELOPE BETWEEN THE INNER ENDS OF SAID LEAD-IN WIRES AND CONNECTED DIRECTLY TO SAID WIRES, SEAL PORTIONS AT THE EXTREMITIES OF SAID ENVELOPE COMPRESSED UPON AND HERMETICALLY SEALED TO LOCALIZED PORTIONS OF THE RESPECTIVE LEAD-IN WIRES EXTENDING THERETHROUGH, LOCALIZED PINCH PORTIONS OF SAID ENVELOPE SPACED FROM RESPECTIVE SAID SEAL PORTIONS AND COMPRESSED UPON LOCALIZED PORTIONS OF THE SAID RESPECTIVE LEAD-IN WIRES ADJACENT THEIR INNER ENDS, THE ENDS OF SAID ENVELOPE BEYOND RESPECTIVE PINCH PORTIONS EXTENDING LATERALLY OF AND A SUBSTANTIAL DISTANCE BEYOND THE MAIN BODY PORTION BY VIRTUE OF A BEND AT RESPECTIVE SAID PINCH PORTIONS. 